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FinTech Lecture 8 : Blockchain

FinTech Lecture 8 : Blockchain

Slides I used for FinTech - Financial Innovation and the Internet 2023 Fall at Graduate School of Business and Finance, Waseda University on December 1, 2023.

Kenji Saito

November 29, 2023
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  1. Financial technology in the living room. Generated by Stable Diffusion XL Beta
    FinTech — Financial Innovation and the Internet 2023 Fall
    Lecture 8 : Blockchain
    Kenji Saito, Graduate School of Business and Finance, Waseda University
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.1/42

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  2. This class is recorded
    Using Zoom
    The recordings could be used for research on (online) learning
    Transcribed for use and anonymized
    Will let you know when the necessity arises
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.2/42

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  3. The lecture slides can be found at :
    https://speakerdeck.com/ks91/collections/fintech-2023-fall
    Trial automatic transcription for lectures will be posted at Discord
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.3/42

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  4. Schedule (provisional)
    Lecture 1 10/6 Overview of FinTech (1) •
    Lecture 2 10/13 Overview of FinTech (2) •
    Lecture 3 10/20 Internet Technology and Governance (1) •
    Lecture 4 10/27 Internet Technology and Governance (2) on-demand •
    Lecture 5 11/10 The World of Apps (1) •
    Lecture 6 11/17 The World of Apps (2) •
    Lecture 7 11/24 Basics of Cryptography and Blockchain •
    Lecture 8 12/1 Blockchain •
    Lecture 9 12/8 Smart Contracts (1)
    Lecture 10 12/15 Smart Contracts (2)
    Lecture 11 12/22 Smart Contracts (3)
    Lecture 12 1/12 Cyber-Physical Society and Future of Finance
    Lecture 13 1/19 FinTech Ideathon
    Lecture 14 1/26 Presentations and Conclusions
    Online presence is possible but not recommended for non-online lectures for interactivity reasons
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.4/42

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  5. Last Week, We Did
    . . .
    Discussion : Imagine API (brief reflection on API concept)
    Basics of Cryptography
    Cryptographic hash function
    Public key cryptography and digital signature
    Zero-knowledge proof
    Assignment Review
    Understanding Blockchain Begins
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.5/42

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  6. Today’s Topics
    Understanding Blockchain
    Beaker/Newspaper Model (physical model of Bitcoin)
    Validity/Existence/Uniqueness layers
    Applicability of Blockchain
    Impossibility and Challenges of Blockchain
    Brief Introduction to Upgrading and Governance of Blockchain
    Assignment — Science Fiction Prototyping
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.6/42

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  7. Before Going into Blockchain,
    a Thought Experiment
    on how to digitize a last will
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.7/42

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  8. Regarding a Digital Last Will (1)
    You may think that using a digital signature instead of a handwritten one, you
    can be sure that the will is authentic without having to rely on witnesses
    But a will is an example that cannot be digitized using conventional thinking
    As you know, a digital signature is made using a private key
    Basic premise of digital signatures is that the signer keeps the private key secret
    Leakage of private key, compromise of signature algorithm, and expiration of public key certificate are the three
    major risks of digital signatures
    However, a will is used only after the death of the person who signed it
    If the person who keeps the private key secret is not present, it can be
    suspected that maybe one of the heirs who has access to the private key
    has tampered or fabricated it
    Timestamps can be easily rewritten or faked
    Even if a notary in the digital age takes care of your will, you have to be suspicious of the possibility of their
    collusion with your heirs
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.8/42

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  9. Regarding a Digital Last Will (2)
    Let’s sort out the requirements
    It must be verifiable by the person and heirs that requirements ↓ are met (instead of believing)
    One can prove that they are the right person who writes or updates the will
    only with their own help (self-sovereignty)
    The will is always written or updated if the person wants it to happen
    (censorship resistance and fault tolerance)
    Once the will is written or updated, it is virtually irreversible – one cannot erase
    it, and one cannot go back in time and falsify it (tamper resistance)
    ⇒ Blockchain was designed to meet the above requirements
    For a will? Never heard of it explained that way?
    OK, replace “write or update a will” with “transfer bitcoins”
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.9/42

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  10. Understanding Blockchain
    Blockchain is a substitute for newspaper (by Satoshi Nakamoto)
    Satoshi him or her or themselves called it “distributed time-stamp server”
    Not a good word for representing a concept (catchy, but manipulating the impression)
    Something implemented by
    Chain of ← actually, backward list of
    Blocks ← actually, sets of data
    For example, we don’t call TV “picture tube” today (or do we?)
    If you name a concept based on how it is implemented, it will quickly become outdated
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.10/42

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  11. What Is Blockchain About?
    Bitcoin’s “Question”
    How do “we send money whenever we want, and
    never let anyone stop us”?
    Distrust of (central) bank money / Sending money → a state transition in a state machine
    Straightforward requirements (BP : Blockchain Properties)
    BP-1: A self-authorized user solely can cause a state transition that is
    allowed in the state machine (self-sovereignty)
    BP-2: Such a state transition always occurs if the authorized user wants it
    to happen (censorship resistance and fault tolerance)
    BP-3: Once a state transition occurs, it is virtually irreversible, and can
    never be denied (tamper resistance)
    Denying = rejection, deletion, alteration, fabrication
    ⇒ Censorship resistance in the broadest sense (no control of the past either)
    Not really perfectly satisfied by blockchain
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.11/42

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  12. Bitcoin’s “Question” and “Answer” (1)
    Bitcoin’s “Question” again
    How do “we send money whenever we want, and
    never let anyone stop us”?
    Distrust of (central) bank money
    Bitcoin’s “Answer”
    Cannot depend on any particular service provider
    ⇒ Exchange digital coins over the Internet by P2P (peer-to-peer)
    What if they deny that they sent a coin?
    ⇒ Use digital signatures (collateral for verifiability and non-repudiability of contents)
    But without public key certificates (that require certificate authorities)
    ⇒ Make public key digest the identifier of a user
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.12/42

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  13. Bitcoin’s “Question” and “Answer” (2)
    Problems that cannot be solved by digital signatures alone
    Need to prevent double spending
    (want to ensure non-repudiation of existence → then it is the same problem as the case of a last will)
    ⇒ Put the evidence of the transaction in newspaper
    What if refused for publishing or service is discontinued?
    ⇒ Place evidence of a transaction in “newspaper” (as collective evidences of events)
    issued by a crowd (everyone has the exact same local copy of the newspaper)
    And thereby records are like locked up in the air
    · Anyone can leave, and when they join again, the records are still there
    Theft of coins based on this idea always follow the story made typical by the
    Mt.GOX or CoinCheck incident
    “Don’t let anyone stop us from spending our own money whenever we want to”
    ⇒ Has to prove that the user is oneself by their own → Zero-knowledge proof of possession of the private key
    → Anyone with the private key is the user oneself
    ⇒ Transaction is verifiable by all but irrevocable → Stolen coins can be tracked but not recovered
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.13/42

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  14. World of Beaker / Newspaper Model (1)
    21,000,000 cm3 (cc) of liquid of no value to mankind
    Contained in a tank
    Individuals can hold as many beakers as they like,
    measuring down to 1
    100
    ,
    000
    ,
    000 cm3 (it has a locked lid)
    Only “editor” selected every 10 minutes on average can
    pump now 6.25cm3 into their beaker
    Chosen by a special lottery
    The winning lottery is held in everyone’s box, and each
    person draws the lottery with all their strength
    → non-stoppable procedure
    Coordinate the proportion of winning lots so that
    someone is chosen every 10 minutes on average
    Volume pumped is reduced by half every about 4 years
    (every 210 thousand pages of “newspaper” described later)
    Started from 50cm3 in January 2009
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.14/42

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  15. World of Beaker / Newspaper Model (2)
    Relatively free flow of fluid between beakers
    Recorded as “a signed article” by the pourer
    Post the article in the “newspaper” made by everyone
    Selected “Editor” verifies the articles and publishes them in
    the last page of newspaper (of which everyone has a local copy)
    Page carries the evidence of winning the lottery
    Editor also gets “overflow” of trades on the page
    If people publish a page with the same page number. . .
    Longer sequence of pages wins
    People sometimes lose the key of their beakers
    Create this digitally, and pretend that it’s a currency
    → Bitcoin
    There is no money or currency that does not need pretension
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.15/42

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  16. Guarantee of Validity ∼ (so-called)
    UTXO Structure
    An input requires a digital signature of the party to which the referenced output is addressed
    Referenced output (= coin) is consumed → never double-spent (UTXO : Unspent transaction (TX) Output)
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.16/42

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  17. Proof of Existence ∼ Hash-chain w/ Proof of Work
    page number : n page number : n+1 page number : n+2
    Cryptographic digest of the previous page
    (must be less than or equal to the target value)
    some extra number (Nonce : Number used Once)
    (random value to make the digest less than or equal to the target)
    Page digest (output by a cryptographic hash function) must be less than or equal to target
    We don’t know how to manipulate the original data to get the right digest
    This is the principle of the lottery, which requires the same amount of cost to fake the history
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.17/42

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  18. Consent of Uniqueness ∼ Nakamoto Consensus
    page number : n page number : n+1 page number : n+2 page number : n+3
    page number : n+1 page number : n+2 page number : n+3
    page number : n+4
    This history is valid
    Sometimes page sequences are split when someone else wins the lottery at about the same time
    A history is the hardest to tamper with when the cumulative cost of lottery for the whole sequence is the highest
    Everyone agrees that such history is the official one (strict consensus is not achieved because it can be overturned)
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.18/42

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  19. Abstract (narrow-sense)
    Blockchain (getting obsolete)
    block_no : n block_no : n+1 block_no : n+2 block_no : n+3
    block_no : n+1 block_no : n+2 block_no : n+3
    block_no : n+4
    Histroy with the largest cost to record or modify (history the most difficult to alter) is chosen
    Cryptographic digest
    of the previous block
    Transactions are
    digitally signed
    To create a block, its cryptographic digest needs to be below some certain number (Proof of Work)
    or one needs to win by voting weighted by the stakes in cryptocurrency (Proof of Stake) [both costly]
    Creator of a block can record the reward
    in cryptocurrency in the block, which is
    effective only when the block is included
    in the chosen history
    Means are provided to confirm
    existence of transactions
    validity existence
    uniqueness
    In case of Proof of Work, the cost of power is balanced against the market value of the native currency
    Everyone confirms that records are not tampered with by the mechanism protected by the price of the native currency
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.19/42

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  20. Proof and/or Message Embedded in block 0
    You can embed data unrelated to Bitcoin in the free
    space of transaction (TX) data
    Text string embedded in the 1st TX of the 1st block
    “The Times 03/Jan/2009 Chancellor on brink of
    second bailout for banks”
    Anyone can verify this
    Specify 0 in the search field of
    https://www.blockchain.com/explorer , proceed to BTC Block
    See the input for the only TX in the block that came up
    Use “Hex to ASCII Text Converter” for example
    What is the intention?
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.20/42

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  21. Applicability of Blockchain
    Possible applications and what you can actually do today
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.21/42

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  22. Possible Applications (as Hyperledger project sees them)
    Financial Assets
    Direct access (no need for mediation), agreed real-time settlements, business rule descriptions, and confidentiality
    Corporate behavior (automating corporate management, especially in financial matters)
    Real-time execution and confidentiality control of share splits, capital reductions and consolidations, share transfers
    and exchanges, mergers, third-party allocation of new shares, etc.
    Supply Chain
    Traceback of materials, and record and search from production, storage to sales (beware of linkage problem)
    Master Data Management
    Only authorized personnel can update and designated reviewers approve it
    Sharing Economy and IoT
    Smart cities/towns, transportation, healthcare/fitness, retail, architecture, education, etc. (implicitly real-time and on
    a large scale) where trust is not necessarily established
    Red letters denote parts that blockchains are not good at
    Within the problems we want to solve, there are sub-problems that have not been solved yet
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.22/42

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  23. Actual Applications to Date
    Currency and Remittance
    Ex. Bitcoin, . . .
    Remittances that bypass banking networks
    That’s a huge impact
    Proof of Existence
    Ex. Proof of Existence, Everledger (in the past), . . .
    Embed arbitrary digests in a blockchain (piggybacking hack)
    There is also a method of embedding a single digest of a large number of records
    Proof that a record has existed and has not been tampered with
    Origin Certification (traceability, tracking and accounting)
    This is the originally intended application category of blockchain
    (an alternative to “newspaper”)
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.23/42

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  24. General Model of Existence and Certification
    EPD

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    Merkle trees are also used within blocks in blockchain to record transactions or states
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.24/42

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  25. Impossibility and Challenges of Blockchain
    Transitional technology, in the process of trial and error
    In fact, a lot of new designs are being tested
    If we do not have governance for (or if we do not know how to accommodate)
    technological changes, we cannot use it in society
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.25/42

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  26. Hash Rate Transitions (Jan. 2009 - Nov. 2022)
    If malicious participants gain half of the hash rate, blockchain cannot be guaranteed to work correctly
    Risky in principle if the hashrate is doubled quickly → It has happened
    On the other hand, what if it doesn’t double rapidly? → Dilemma of providing room for malicious participants
    What if it suddenly halves? → Very risky in principle, and it also happened
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.26/42

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  27. Reality vs. Blockchain
    A thought experiment
    You want to start a new business on the beach:
    If a customer pays in bitcoin, a drone flying overhead will drop them a can
    of juice
    When should the drone drop the can?
    Reality that goes in real-time and blockchain’s behavior are very different
    But as a business decision, a risk taker can drop the canned juice the
    moment they detect a payment
    As long as they are in a position to use social infrastructure, they can act
    disruptively
    Not because it is a perfect technology
    But because it is a fairly cheap platform (cost is paid by the miners)
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.27/42

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  28. The DAO Incident (uncovered governance challenges)
    The DAO, an autonomous decentralized investment fund built on Ethereum
    Split (fund split) was recursively called, and 360,000 ETH (5 to 6 billion yen) was stolen
    (2016/6/17)
    Choices
    Do nothing
    Soft fork (maintains compatibility → freezes the address of the thief)
    Funds are not returned
    Hard fork (No compatibility → rewrites history; who controls the present controls the past)
    Worst occurrence of “Oneness Trap” (described later) in a sense
    Community chose “hard fork” ! (executed on 2016/7/20)
    “Most interesting. Gravity’s silhouette remains, but the star and all its planets have disappeared. How can this be?”
    “Because someone erased it from the archive memory.” — from Star Wars: Episode II – Attack of the Clones
    So the incident never happened
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.28/42

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  29. Scaling Out
    Question
    There is one ATM that always has 10 people in line
    Sorry if you are in an advanced environment, and you don’t know what we are talking about
    (or even wonder what an ATM is) ;)
    What happens to the number of people in the queue if we add one ATM?
    Other conditions remain the same
    cf. Daisuke Yamazaki, “Rethinking Scaling Out” (in Japanese)
    http://www.slideshare.net/yamaz2/ss-58813038
    Performance problems can be solved by adding a server
    ⇒ The system scales out
    Blockchain does not scale out in its bare form (because everyone makes and maintains a replica)
    Improvement is possible if you see it as a KVS (Key-Value Store)
    Because of the distributed KVS technology
    But you might lose autonomy
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.29/42

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  30. Scaling Out and Blockchain
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    In blockchain, the cost of maintaining data structures rises linearly as transactions increase
    It does not scale out Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.30/42

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  31. Blockchain’s “Oneness Trap”
    It does not scale out
    Adding more nodes does not solve or mitigate performance challenges
    Must be “the world is one” to work
    System does not work correctly if the network is partitioned by a large-scale disasters or
    political change
    Difficulty of governance to advance technology
    You cannot “try something different partially, and if it works, apply it to the whole”
    Impossibility of governance :
    Agreement by the “whole” must be maintained, but the “whole” cannot be defined
    ⇒ Powered few changes the technology instead
    ⇒ Those are disadvantages of non-decentralized nature of blockchain
    Conversely, there are great expectations and potential for truly decentralized “record fixation
    device in the air” Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.31/42

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  32. Incentive Mismatch
    Ethereum cannot survive as an application platform if ETH as a currency
    crashes and declines
    Supported by validators’ motivation to get ETH
    When the value of ETH drops, validators withdraw
    Can people who want to run apps (smart contracts) buy ETH to maintain the price?
    If ETH’s market participants are primarily app users, may be
    . . .
    (but they aren’t)
    The design of the raw Bitcoin is goal-consistent, but
    . . .
    In other words, “Bitcoin cannot survive if BTC declines” would be fine
    But as proof applications such as Proof of Existence advance, similar problems arise
    Either way, the future of the system depends on the interests of the miners/validators
    ⇒ Need to separate application platforms from currency systems
    That is where the recent ledger technology is going, hopefully (because many still aren’t)
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.32/42

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  33. What is the True Worth of Blockchain?
    Roughly speaking, what’s the thing you can never do without blockchain?
    Ex1
    : Digitizing the last will and testament (in a thought-experiment sense)
    After the death of the person, the private key used for the digital signature may no longer be a secret
    Can’t believe a notary saying, “it is as signed before the death” (possible collusion with malicious heir)
    Ex2
    : Online banking passbook data as proof (for the liabilities of banks)
    If you download it as a CSV file, the data anyone can create is not considered as evidence
    Even with the digital signature of the bank, once the private key is leaked, the data can be created by anyone
    Prove “data digitally signed at cetain past date has not been tampered with”
    (instead of believing those who insist so)
    “The Last Will Test” is to ask them if they can do that with their blockchain
    A test to see if something that someone has been pitching as “it’s a blockchain” really makes sense
    An idea (hash-chain with proof of work) that may satisfy this true worth, combined with existing technologies around the
    idea is the Bitcoin blockchain
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.33/42

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  34. How Well Is It Realized Today?
    Is there a technology that can pass the “last will test”?
    Public blockchain may pass the test while the market value of the native currency is high
    Defense such that it would cost a lot to tamper with
    When the price of the native currency drops or crashes it becomes unreliable
    Private ledger systems in general only insist, so they do not pass the test
    Mostly, “blockchain made and operated by XXX Inc.” is meaningless ← please be careful
    We are building new technology to make it pass the test
    BBc-1/BBc-2 (Beyond Blockchain One/Two; https://github.com/beyond-blockchain) (just an example)
    There is an inherent challenge of linkage between records and entities
    Includes areas that cannot be solved by engineering alone
    (does the public key really belong to the person?)
    Including the openness of the source code, it is roughly the problem of
    . . .
    “How can we trust automated mechanisms?”
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.34/42

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  35. Brief Introduction to Upgrading and Governance
    of Blockchain
    Weaknesses are not left untouched, but continue to be improved
    But governance issues remain
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.35/42

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  36. Enhancements to Bitcoin Blockchain
    Virtualization – Open Assets Protocol (no fork)
    Interpret transaction data in a specific way so that quantities independent from BTC can be defined and used
    Bug fix – Segregated Witness (SegWit) (soft fork)
    Signatures are separated from the transaction body
    Better privacy and conciseness – Taproot (and Schnorr signatures) (soft fork)
    Scripts can be partially disclosed by expressing them in Merklized Abstract Syntax Trees (kind of Merkle trees)
    Quickness – Payment channels (no fork)
    Only write to the blockchain when the channel is opened and closed, and in between you can make fast payments
    Conceptually, connected payment channels form a Lightning Network
    How do we upgrade?
    Soft fork : miners vote by setting a bit in a block header
    Wait, voting? Is it an Internet way?
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.36/42

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  37. Payment Channel (Bitcoin’s case)
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    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.37/42

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  38. Science Fiction Prototyping
    What about it?
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.38/42

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  39. Why Science Fiction Prototyping?
    What is Science Fiction?
    Fantasy based on or disguised as the thoughts and ideas of science and technology
    The world with existing science and technology is the real world
    Ex1
    : Medical drama
    Ex2
    : Economic novels
    The world with science and technology unknown to the real world → Fiction
    Ex1
    : Medical drama with nano-machines
    Ex2
    : Drama with digital currency that depreciates (my book “NEO in Wonderland”)
    Designing new media and putting it into society = living science fiction
    To work out plans for that = to write science fiction
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.39/42

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  40. Assignment
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.40/42

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  41. Assignment 4. “Smart Contracts”
    Please think freely with the image of the word “smart contract” to fantasize a
    specific application example, and state the application briefly
    That is, go ahead and write a very short science fiction
    Deadline and how to submit
    December 5, 2023 at 17:59 JST
    From Moodle (mandatory) (Q&A forum)
    So that your classmates can read your report, refer to it, and comment on it
    Optionally, you can also post to #assignments channel at Discord
    So that anyone in our Discord can read your report, refer to it, and comment on it
    Just plain text, and be concise, please
    You may want to apply Kent Beck style for abstracts (4 sentences)
    (problem) (why it is a problem) (startling sentence) (consequences) of a story
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.41/42

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  42. Have a Nice Weekend and See You Next Week!
    Lecture 8 : Blockchain — FinTech — Financial Innovation and the Internet 2023 Fall — 2023-12-01 – p.42/42

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